1. Field of the Invention
The present invention relates to a block working blade unit, a block chipping machine and a block chipping process which are incorporated into a block production line, and which are used to work the upper surface corner parts of blocks in a short time.
2. Description of the Related Art
Conventionally, mainly tumblers have been used as means for working the corner parts of concrete blocks and the like. Ordinarily, in such tumblers, a cylindrical rotating body with a length of 3 to 6 meters is disposed at an inclination. The working of concrete blocks using such a tumbler is accomplished by putting into the tumbler concrete blocks that are conveyed by means of a conveyor or the like via the feed-in opening of the tumbler, which is disposed in a location that is higher than the discharge opening, and rotating the tumbler. The surfaces of the concrete blocks are roughly chipped off or scrapped away by mutual contact inside the rotating tumbler. Concrete blocks whose end portions have been roughly chipped off are discharged from the discharge opening of the tumbler.
In the case of such a process, since the corners are chipped or cut away by causing the concrete blocks to contact each other inside the rotating tumbler, a considerable working time is required; furthermore, the worked concrete blocks are discharged from the discharge opening without being arranged in a row. Since the worked concrete blocks are ordinarily shipped after being stacked, it is necessary to line up the concrete blocks following working, and to convey these concrete blocks to a stacking machine. Accordingly, in cases where a conventional chipping process using a tumbler is used, a process in which the concrete blocks discharged from the tumbler are rearranged for the stacking machine by hand is required.
Furthermore, there have also been methods in which concrete blocks lined up on a conveyor are conveyed “as is”, and the surfaces of these concrete blocks are worked by a chipping machine. For example, such methods include shot blast working (e.g., see Japanese Patent Publication No. 1-156010A) and methods in which a high-pressure water current or air stream is caused to jet onto the worked surfaces (e.g., see Japanese Patent Publication No. 2001-269920A and Japanese Patent Publication No. 2000-301523. However, these methods suffer from problems in terms of precision and increased size of the apparatus. Furthermore, in the case of methods that cause the jetting of a water current or air stream, it is difficult to achieve a worked surface with a feeling of natural rough chipping on the blocks by surface working.
In addition, there are also methods in which the surfaces of concrete blocks are worked using bush hammers or connected nail-form projections. In the case of such methods, however, it is difficult to chip only the upper surface corner parts of the concrete blocks. Moreover, in cases where the upper surface corner parts of blocks are worked using the nail-form projections, after the long sides of the corner parts or short sides of the corner parts of the blocks are worked, it is necessary to work the other sides of the corner parts again after rotating the blocks 90°.